[The role of computed tomography in the diagnosis and treatment of malignant tumors of the nasal cavity, paranasal sinuses and nasopharynx].

We studied the value of computed tomography (CT) in diagnosis and treatment of primary malignant tumors of the sinonasal cavities and nasopharynx, and reached the following conclusions. 1) In maxillary carcinomas, bone destruction is always seen on CT. When bone destruction is not apparent despite invasion to the adjacent site, malignant lymphoma or plasmacytoma is suggested. 2) In defining the tumor extent of maxillary SCC, CT is more reliable than maxillotomy, and is equal to maxillectomy. However, clouding of the sinus without bone destruction remains a problem, since this finding can be caused by either tumor invasion or obstructive sinusitis. 3) In maxillary and nasopharyngeal SCC, CT frequently reveals tumors to be more extensive than previously suspected following physical and conventional x-ray examinations. Therefore, the T-stages of these tumors are often upstaged to more advanced ones. 4) CT is of great help in identifying candidates for surgery in maxillary SCC, and in planning radiation therapy for nasopharyngeal and sinonasal tumors. Dose distribution curves displayed directly on the CT slices are becoming essential tools for radiation oncologists. After the introduction of CT, treatment results in cases of nasopharyngeal SCC have improved, probably due to better definition of the tumor volumes. 5) CT is also used for observing tumor response after therapy and for follow-up. In summary, CT is now indispensable in the management of malignant tumors of these sites.